The patent literature includes various examples of single brew beverage filter packages or cartridges for use in brewing apparatus. For example, U.S. Pat. No. 5,325,765 discloses a beverage filter cartridge that includes an impermeable pierceable base having a predetermined shape and an opening at one end. The base is formed of polystyrene, ethylene vinyl alcohol and polyethylene. A self-supporting wettable filter element is disposed in the base. The filter element may be made of a lightweight, two-phase heat sealable paper of cellulosic and synthetic fibers. The synthetic fibers may be PVC or polypropylene so that they are compatible with the material of the base and are therefore easily sealed to the base in communication with the opening in the base using heat, ultrasonic energy or microwave energy. The filter element has a form different and smaller than the predetermined shape of the base so that the filter element diverges from the base and divides the base into two sealed chambers, a first chamber for storing an extract of the beverage to be made, and a second empty chamber for accessing the beverage after the beverage outflow from the filter has been made by combining a liquid with the extract. An impermeable pierceable cover is provided sealingly engaged with the opening in the base to form an impermeable cartridge. U.S. Pat. No. 5,840,189 discloses a somewhat similar beverage filter cartridge.
While the cartridges of those patents are suitable for their purposes they are nevertheless somewhat complex in construction, e.g., they require a self supporting, e.g., plastic material, outer base in which the filter element is suspended to break up the interior of the base into the two chambers.
In Published U.S. Application 2005/0287251 there is disclosed a disposable beverage filter package that does not make use of an outer base. In particular, the filter package comprises a flexible and permeable filter pouch in the form of a cone having a sidewall extending downwardly from a top opening to a closed bottom. The pouch is suspended from and supported exclusively by an imperforate impermeable lid configured and arranged to close the top opening and to coact with the pouch in defining an enclosed chamber. The side wall of the pouch has an upper region with a permeability that is greater than that of a lower region. This difference in permeability may be provided by various means, e.g., by adding an inner cone shaped insert of the same material as that of the outer wall. A dry beverage medium is loosely contained within the filter pouch. The lid is piercable to admit a flow of heated liquid under pressure into the chamber, with the permeability of the pouch being such that the admitted liquid is retained temporarily in the chamber for infusion with the beverage medium before permeating through and flowing downwardly along the exterior of the sidewall as a liquid beverage.
While the cartridge of that application appears generally suitable for its purposes, it is still somewhat complex in construction (e.g., makes use of a conical filter whose lower end, in which the beverage brewing ingredient will be concentrated, is of thickened or double wall thickness), is somewhat limited in the amount of beverage brewing ingredient it can hold, and may leave something to be desired from the standpoint of effectiveness in brewing the beverage.
Thus, there presently exists a need for a disposable beverage filter cartridge for use in beverage brewers, with the cartridge being low in cost, simple in construction and preferably compostable and biodegradable so that it can be readily and safely disposed of after use. The subject invention addresses that need.